Giovanni Trapattoni has experienced cruel cuts during his four years in charge of the Republic of Ireland, most infamously at the hand of Thierry Henry, and he felt that further injustice played a part in the 3-1 defeat here against Croatia.

The manager argued that Nikica Jelavic was "two metres offside" before he scored Croatia's second goal and that Ireland were also denied what appeared to be a clear penalty when Gordon Schildenfeld went through the back of Robbie Keane. Yet Trapattoni refused to look beyond the shortcomings of his own players as he considered a brutal blow to his team's prospects. He was in magnanimous mood with regard to Slaven Bilic's Croatia, who he accepted were the "better team".

The Italian simply attempted to come to terms with how his team had under-performed and been guilty of uncharacteristic defensive mistakes. Ireland had entered the tournament on the back of 14 matches without defeat, during which time they had conceded only three times. Croatia matched the tally in 49 minutes.

"Our performance was not like our other performances in our other games," Trapattoni said. "Many games we have played better and we have not conceded. Tonight we conceded three. I cannot speak about the other situations. They deserved to win. They were superior in midfield."

Ireland had recovered from the set-back of conceding a soft opening goal to Mario Mandzukic in the early running, when they appeared to lose their focus in what was an intense and pulsating atmosphere. "Maybe we had tension in this moment," Trapattoni said. But after Sean St Ledger had punished lax marking from the Croatia defender Vedran Corluka, the game turned on Jelavic's goal.

From Luka Modric's initial shot, Jelavic was in an offside position, although it was questionable whether he could be deemed to be interfering with play. In the second phase, after the ball had ricocheted, it was the Ireland defender Stephen Ward's sliced clearance that ushered in Jelavic, whose flicked finish bristled with quality. Croatia's third seemed to confirm that it would not be Ireland's night.

After more loose marking, Mandzukic's header hit the post, then Given and then the net. "The two goals killed us just before half-time and just after it," said the captain, Robbie Keane. "It was always going to be uphill after that. It was a tough game. I'm gutted that we weren't able to get the result for the Irish support. They were in good voice as usual."

"One mistake is us [on the first goal], one mistake is also the referee [on the second]," Trapattoni said. "Maybe Shay Given did not see the ball on the first goal because he had three or four players in front of him. And there was the deflection [on the cross]. But the second goal was clearly an offside position. Obviously, it was a very important goal."

The penalty controversy in the 62nd minute came after Ireland had played on as Mandzukic lay injured at the other end of the field. It was put to Keane that the penalty might have been given under different circumstances. "Yes, I think so," he replied. "It was definitely a penalty, no question [but] because all of their players and fans were calling for us to kick the ball out ... You'd have to ask the referee if he had that in the back of his mind."

The Ireland squad was deflated as they departed Poznan and now know they must get a result against Spain on Thursday to avoid an early exit. Their final Group C tie is back at this venue against Italy next Monday. But Trapattoni, who insisted that Given had been fully fit and not undermined by his recent knee and muscle trouble, forced himself to remain optimistic. This was only his third competitive defeat with Ireland.

"Psychologically, we have to recover and believe again," Trapattoni said. "We have to remember how many games we played without conceding a goal and when we didn't lose. We have another 90 minutes [against Spain]. And Croatia must play Italy.

"We have to believe in what we have done until now. We have faced a very strong and technical team but every game in this Euro can be a good surprise. We have to believe this. Until now, we have scored goals and not conceded them. We cannot forget everything."